Mastering the Art of Electrical Conduit
Running electrical conduit on the surface of a wall is an easy way to add wiring to a workshop, garage or basement or anywhere else there are no open stud cavities. And electrical metallic tubing (EMT) is a perfect choice. It’s strong, cheap and easy to bend once you learn how. After the conduit and boxes are mounted, you push or pull wires into them, and connect the wires to the switches, outlets, lights or other devices you’re installing. These tips will help you get the job done right.
Don’t Want to Bend Conduit? Use Fittings Instead
They may cost a little more and look a bit less professional, but if you have just a few bends to make and don’t want to buy a bender and learn how to use it, you can use fittings instead. You can turn inside corners and change direction with pre-bent 90- and 45-degree angles connected to straight sections of EMT with couplings. Buy pulling ells to avoid bending the conduit around outside corners. You can also use offset connectors instead of making an offset bend where EMT connects to boxes.
Use Your Foot
Clamp Conduit for Easy Cutting
Large slip-joint pliers are all you need to hold conduit firmly in place while you cut it. Clamp the conduit to a workbench, sawhorse or even a wooden ladder step with pliers. Then mount a sharp, 32-tooth-per-inch hacksaw blade in your hacksaw frame and cut the conduit. After you make the cut, it’s important to remove any metal burrs from inside and outside the conduit. Insert the blade of a screwdriver into the conduit and swivel it around to flatten any burrs on the inside of the pipe. Twist the jaws of slip-joint pliers around the outside of the conduit to remove burrs there.
Avoid Offsets With Conduit Hangers
Conduit should be supported within 3 ft. of a box, with additional attachments no more than 10 ft. apart. One method is to clamp the conduit tight to the wall with single-hole conduit straps. But if you do this, you’ll have to either bend an offset in the conduit or use an offset fitting where the conduit enters boxes. You can avoid offsets by attaching the conduit with conduit hangers. These hangers hold the conduit off the wall so it can run straight into boxes with no offset.
To install conduit hangers, hold the conduit against the wall where you want it and make a mark on the top and bottom where the hanger will go. Remove the conduit, center the strap between the marks and attach it with a screw. It’s best to locate the hangers over framing for a solid attachment, but if you can’t, use a drywall anchor instead. Now simply slip the conduit into the hanger and secure it with the included bolt and nut.
Save Time?Push Rather Than Pull Wire
One method of getting wire from one box to the other is to insert a fish tape into the conduit on one end, push it through to the other end, hook the wires to it and pull them back through. But with the right technique, you can often simply push the wires through the conduit, especially if there aren’t too many bends and you’re using solid rather than stranded wire. To do this, first choose one wire for the leader and make a bend on the end. Then use electrical tape to attach the remaining wires to the lead wire. Starting at the open end of the loop, wrap the tape tightly around the wires to make sure they stay attached. When you reach the end, cut the tape and fold it back on itself to make a tab. This makes it easier to remove the tape. Then simply push the bundle of wires through the conduit. The bent end of the lead wire will prevent it from getting hung up on fittings.
Use a Pulling Ell at Outside Corners
You can’t just go around an outside corner with a 90-degree bend or fitting, because the wide radius would cause the conduit to stick out into the room. You can bend conduit to go around an outside corner, but it requires two bends and is a little tricky. A 90-degree pulling ell provides the easiest solution. To use it, remove the cover and push or pull the wires to the bend. Then bend the wires around the corner and push or pull them to their destination. The last step is to coax the wires into the fitting. Have a helper gently pull one wire at a time while you work it into the ell. When all the wires are neatly tucked into the pulling ell, replace the cover.
Tighten Box Connectors Easily
To maintain a good ground and provide a solid attachment, EMT is connected to metal boxes with fittings called conduit connectors. After you’ve removed one of the knockouts from the metal box, you insert the connector into the hole and thread on the retaining nut. To achieve a good ground connection, it’s important to make sure the nut is really tight.
Here’s an easy method to tighten the nut. Before you mount the box, thread the nut onto the connector and hand-tighten it. Then position the connector so that the setscrew is a quarter turn counterclockwise from the front of the box. Grab the connector with pliers and twist it a quarter turn to tighten it. With this method, the nuts will be tight and all of the setscrews will be facing out.
Tweak Bends With the Bender Handle
If your conduit bend isn’t quite right, an easy way to adjust it is to slide the handle of the bender over the conduit and bend it a little one way or the other. And here’s how to know if your 90-degree bend is really 90 degrees. After bending the conduit, place one leg of the bend vertically against the wall and the other leg on the floor. If the vertical leg is parallel to the wall, the bend is 90 degrees. If it’s away from the wall at either the top or the bottom, use the conduit handle to fix the problem.
Use a Big Box Extension
If you’re planning to run conduit on a finished wall and use an existing electrical box for power, you’ll need to start by adding a box extension. If the existing box is a single-gang box, you could use a single-gang box extension. But a much better method is to add a 4-in. square box extension with a single-gang cutout in the back. The larger box extension gives you more room to easily connect wires and add devices. It also looks better because it covers up any ragged edges of drywall around the single-gang box, and it will match the other 4-in. square boxes you’ll be installing for the rest of the system. The only drawback to this tip is that these boxes can be difficult to find. You may have to order one online or go to an electrical parts supplier rather than the local home center.
Remember to Ground the Conduit
In an EMT wiring system, the metal conduit functions as the ground. You don’t need a separate ground wire. But you do need to make sure the conduit itself is securely connected to a known ground.
In the example shown here, the metal box extension is connected to a plastic box. Connect the ground wire in the plastic box to the metal box extension by screwing a No. 10-32 grounding screw into the threaded hole in the metal box extension and connecting a short length of copper wire (grounding pigtail) to the screw. Then connect the grounding pigtail to the ground wire or wires in the plastic box with a wire connector. Add grounding pigtails to connect any devices you’ll add to the box.